Setup and Configuration
This may go a bit far on the tech talk but bare with me. Here's how the installation goes:
Out of the box, the Black2 appears as *only* a 120GB SSD. The HDD is there, but not visible to the host system. Here's what it looks like when connected to another system:
There is a good reason for this. What you want to happen is to either clone or install your OS fresh to the SSD portion. The best way to prevent the Windows installer or cloning software from partitioning into the HDD space is to simply make that space inaccessible during that portion of the setup. Once the OS is installed and you're booted up on the SSD portion of the Black2, you download and install the driver package from WD:
This is a very simple installer that leaves almost no footprint on the host system. Contrary to what you may think, there is no specific or special storage driver that allows access to the HDD portion. During install, the 'driver' instructs the Black2 to open up the additional space, which it does by tacking the HDD space onto the end of the SSD space. After a reboot (if necessary), the software kicks back in and partitions the HDD space for you. The end result looks like this (seen connected to a test system with its own OS):
Now I know what you're thinking. You're probably wondering what happens if, say, your OS gets stuck in a blue screen loop, or gets infected with a virus. How can you access the 1TB of space without being able to boot the OS? The answer to that is simpler than you think. The software is not really a 'driver'. Once it's been installed and 'unlocks' the 1TB appended onto the SSD, it stays there. You could remove the Black2 from the installed system and connect it to a completely different system (via SATA, USB, whatever), and the full 1.1TB drive will appear, just as it did in the above pic. This applies even if the system you connected it to has never seen the Black2 driver software. Basically the unlock / driver install process is only there to ensure the HDD space is untouced during initial install and that the second HDD partition is placed correctly.
WD has also considered the above scenarios in the design of their software installer. If, say, you needed to reinstall Windows for whatever reason. So long as you don't touch the HDD partition, you can safely reformat and reinstall in the SSD space. The HDD partition will persist. Once in your freshly installed Windows you may choose to reinstall the Black2 software, and during that process it will gracefully erorr out at the end, where it would normally create the HDD partition (as it's already there).
If you inadvertently delete the HDD partition, simply uninstall the software (it requires the HDD partition removed before it will proceed regardless), and then reinstall it to re-create the partition. I highly recommend letting the software do this as in my testing it creates that partition at a slightly different offset than Windows would by default. Operating on a Windows-created partition caused odd stutters and hiccups, and I suspect that was due to the beginning of that partition crossing over the SSD/HDD boundary. As a final note, the uninstallation process also re-shrinks the addressible space to that of the SSD, priming it for a fresh OS install without the worry of making the partition too large and crossing into the HDD address space.
Given that the HDD portion is tacked onto the SSD portion and can not be accessed directly, benches run on the combined drives act, well, weird. See for yourself:
Benches result in a combination of both units. Prior to installing the software, the Black2 can be tested like any other SSD, but testing the HDD portion means you're limited to file-based benches or ones that can test specific LBA ranges.